Technical Field
The present invention relates to a water level measuring device that uses radio waves in the millimeter wave band, for example.
Background Art
There are methods of using ultrasonic waves, laser, radio waves, or the like to measure the state of a paved road surface such as that of a sidewalk or road. Document 1, for example, discloses a road surface state detection system including a radio wave sensor transmitting radio waves toward a paved road surface and receiving reflected waves from a reflection surface, a controller calculating the distance from the radio wave sensor to the reflection surface and a reflection intensity of the reflected waves, and a determination unit determining whether the state of the paved road surface is dry, wet, submerged, or frozen based on the calculated distance to the reflection surface and the reflection intensity of the reflected waves.